The term corned refers to the tradition of using large salt granules the size of corn kernels to preserve the meat. The corned beef you buy in the store, ready to boil, is often stuffed full of nitrates and curing salts. When you make it yourself, you know what’s in it. Many start-from-scratch recipes suggest brining for anywhere from four days to three weeks, but poking the meat with a knife or a sharp metal skewer allows the brine to penetrate more quickly, significantly shortening the corning process.